Initial import

src/shared/stdio.ts

@@ -0,0 +1,42 @@
+import { JSONRPCMessage } from "../types/index.js";
+import { validateMessage } from "./message.js";
+
+/**
+ * Buffers a continuous stdio stream into discrete JSON-RPC messages.
+ */
+export class ReadBuffer {
+  private _buffer?: Buffer;
+
+  append(chunk: Buffer): void {
+    this._buffer = this._buffer ? Buffer.concat([this._buffer, chunk]) : chunk;
+  }
+
+  readMessage(): JSONRPCMessage | null {
+    if (!this._buffer) {
+      return null;
+    }
+
+    const index = this._buffer.indexOf("\n");
+    if (index === -1) {
+      return null;
+    }
+
+    const line = this._buffer.toString("utf8", 0, index);
+    this._buffer = this._buffer.subarray(index + 1);
+    return deserializeMessage(line);
+  }
+
+  clear(): void {
+    this._buffer = undefined;
+  }
+}
+
+export function deserializeMessage(line: string): JSONRPCMessage {
+  const message = JSON.parse(line) as JSONRPCMessage;
+  validateMessage(message);
+  return message;
+}
+
+export function serializeMessage(message: JSONRPCMessage): string {
+  return JSON.stringify(message) + "\n";
+}